Problem: On Saturday, Nadia's parents gave birth to twins and named them Ishaan and Vanessa. When they were first born, Ishaan weighed 8.54 pounds and was 19.5 inches tall, and Vanessa weighed 6.67 pounds. How much did the babies weigh in total?
Answer: To find the weights of the 2 babies, we need to add their weights together. Ishaan's weight + Vanessa's weight = total weight. ${8}$ ${5}$ ${4}$ ${6}$ ${6}$ ${7}$ ${+\vphantom{0}}$ ${1}$ ${2}$ ${5}$ ${1}$ Together, the babies weigh 15.21 pounds.